This invention relates to the displacement of nuclear iodine substituents from an iodobenzene with gaseous chlorine.
The prior art teaches that the treatment of benzene bearing nuclear iodine substituents with gaseous (molecular) chlorine does not displace the iodine substituents. See, e.g., J. Am. Chem. Soc., 79:4187-4191 (1957); Huyser, Methods in Free Radical Chemistry, p. 134, Marcel Dekker (1969). Milligan et al., J. Am. Chem. Soc., 84:158-162 (1962), teach that iodine substituents are displaced by certain more active chlorinating agents, such as iodine monochloride, in an irradiated system. However, the prior art is deficient in that it fails to identify an economical manner in which chlorinating agents can be used to displace nuclear iodine substituents in iodobenzene mixtures.
It is particularly desirable in the preparation of chlorobenzenes from chlorine and benzene or monochlorobenzene that a method is identified to displace nuclear iodine substituents which result from the presence of iodine in the chlorine feed or from other sources.